TOPIC - Tooth Phone(R) Auditory Device - TPAD ABSTRACT The Tooth Phone(R) Auditory Device - TPAD is new alternative device to the only direct bone conduction hearing aid currently accepted by the Food and Drug Administration (FDA) for the treatment of certain specific types of hearing loss. Unlike the precedent FDA approved device that uses an osseointegrated implant as the site for skull stimulation, the TPAD uses a natural tooth. Compared to the precedent device, the TPAD has many important advantages such as cost, safety, longevity, fidelity, and cosmetics. In the TPAD system, ambient speech and sound is picked-up by a microphone and radio transmitted to a removable orthodontic-like retainer worn on the palate. An audio processor and novel transducer (actuator) embedded in the retainer then transmits the speech vibrations via the bone conduction pathway to the cochlea. Numerous prior studies have been performed on the TPAD during development of a related voice communication device for the US military. The objective of Phase 1 is to show that the teeth are equivalently sensitive to sound input when compared to a dental implant within the same subject. To help demonstrate this objective, a new methodology is proposed in which a novel accelerometer (sensor) is attached to the teeth. The sensor records skull vibrations from different input devices and skull stimulation sites. This methodology can provide valuable insights into the bio-physics of bone conduction transmission. Through frequency analysis of skull vibrations, the sensor can demonstrate the nature of skull harmonic overtones, and potentially help solve the question of how and why individuals with single- sided deafness can localize sound. The objective of Phase 2 is to build and test an auditory device that can pass FDA 510-K equivalence requirements. PUBLIC HEALTH RELEVANCE: This project will provide an auditory device alternative to the widely accepted Bone Anchored Hearing Aid or Baha(R) . It also introduces a novel tooth sensor instrument that can be used for the direct measurement of within-subject bone vibratory patterns and frequency responses.